sensor AUDI A4 1996 B5 / 1.G AFC Engine On Board Diagnostic Multiport Fuel Injection Service Manual

01-56

Output on GST and/or on
VAG 1551 scan tool Possible malfunction cause

Malfunction repair
P0173 / 16557
Fuel Trim Malfunction (Bank 2) Air leak in the area of the manifold

- Find and repair leak

Malfunction cause found: Yes
No

- Erase DTC memory, test drive and
check DTC memory again

Oil diluted (fuel in the oil) because
of frequent cold starts for driving short
distances

- Check and change oil if necessary
MIL Status:
MIL lights up after 2 Trips Malfunction cause found: Yes
No

- Erase DTC memory, test drive and
check DTC memory again

Mass Air Flow (MAF) sensor -G70-
supplies false signal

- Check Mass Air Flow (MAF) sensor -
G70- page 24
-81

For troubleshooting Display
groups 006, 008, 009 and 010
Malfunction cause found: Yes
No
Continued next page

- Erase DTC memory, test drive and
check DTC memory again

Oil burning with faulty piston

Repair Manual, 2.8 Liter V6 2V Engine
Mechanical, Engine Code(s): AFC, Repair - Check compression pressure
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Group 15


Malfunction cause found: Yes


- Erase DTC memory, test drive and
check DTC memory again
Note:
The malfunction "P0170 / 16554" is set in the learning process as soon as the difference between a newly learned (HO2S)
learning value and any optional stored oxygen sensor learning value is greater than 8%.
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01-57

Output on GST and/or
on VAG 1551 scan tool
Possible malfunction
cause
Malfunction repair
P0174 / 16558
System too Lean (Bank
2) Malfunction P0171 /
16555
"System too Lean (Bank
1)"
Also in DTC memory
No

Yes

- If the fuel-air mixture is too lean for both cylinder banks, a
malfunction must be present that leads to faulty mixture
formation for both banks (B1 and B2) Troubleshooting
per Diagnostic Trouble Code (DTC) table, page 01
-53


Malfunction cause found:
Yes
No

- Erase DTC memory, test drive and check DTC memory
again
MIL Status:
MIL lights up after 2
Trips Leaks in the intake
system for bank 2 up to
Heated Oxygen (HO2S)
sensor 2 -G108-

- Find and repair leak

Malfunction cause found:
Yes
No

- Erase DTC memory, test drive and check DTC memory
again

Leaks in intake system

- Find and repair leak
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Notes:
If the malfunction "P0174 / 16558" is set, the oxygen sensor control has exceeded the learning value limit in the "rich"
direction, but the (HO2S) still recognizes "mixture too lean".
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01-59

Output on GST and/or on VAG
1551 scan tool Possible malfunction
cause
Malfunction repair
P0175 / 16559
System too Rich (Bank 2) Malfunction P0172 /
16556
"System too Rich (Bank 1)"
Also in DTC memory
No
Yes

- Fuel pressure too high. Check system
pressure and residual pressure page 24
-20

Malfunction cause found:
Yes
No

- Erase DTC memory, test drive and check
DTC memory again
MIL Status:
MIL lights up after 2 Trips Fuel injector (Bank 2)
does not close or leaks

- Check fuel injection quantity and for leaks
page 24
-33

For troubleshooting Display
groups 006, 008, 009 and 010
Malfunction cause found:
Yes


- Erase DTC memory, test drive and check
DTC memory again
Notes:
If the malfunction "P0175 / 16559" is set, the oxygen sensor control has dropped below the learning value limit in the "lean"
direction, but the (HO2S) still recognizes "mixture too rich".
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01-60

Output on GST and/or on
VAG 1551 scan tool Possible malfunction
cause
Malfunction repair
P0171 / 16555
System too Lean (Bank 1) Malfunction P1250 /
17658 "Fuel Level Too
Low" also in DTC memory
No
Yes

- For malfunctions that can be caused by fuel problems
(e.g. fuel system too lean), the malfunction "Fuel Level
Too Low" is also set if there is less than 12 liters (12.7 qt.)
fuel in the tank check tank level and fill tank if necessary
P0174 / 16558
System too Lean (Bank 2) Malfunction cause found:
Yes
No

- Erase DTC memory, test drive and check DTC memory
again
MIL Status:
MIL lights up after 2 Trips Large air leak quantity
in intake system to Mass
Air Flow (MAF) sensor -
G70-

- Determine cause of air leak and repair
For troubleshooting
Display groups 005, 006,
007, 008, 009 and 010
Malfunction cause found:
Yes
No
Continued next page

- Erase DTC memory, test drive and check DTC memory
again
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01-61


Fuel system pressure too low because of:
- Leaks in the area of the fuel lines or the fuel distributor strip
- Vacuum line to the fuel pressure regulator or fuel pressure
regulator faulty
- Fuel filter plugged
- Fuel pump delivery quantity too low

- Check system pressure and residual pressure
page 24
-20


Malfunction cause found: Yes
No

- Erase DTC memory, test drive and check DTC
memory

EVAP canister purge regulator valve -N80- sticks
mechanically in closed position

- Check EVAP canister purge regulator valve -
N80- page 24
-58


Malfunction cause found: Yes


- Erase DTC memory, test drive and check DTC
memory
Notes:
If the malfunctions "P0171 / 16 555 and P0174 / 16558"are set, is set, the oxygen sensor control has exceeded the learning
value limit in the "rich" direction, but the (HO2S) still recognizes "mixture too lean".
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01-62

Output on GST and/or on VAG
1551 scan tool Possible malfunction cause

Malfunction repair
P0300 / 16684
Random Misfire Detected
_______________________
P0301 / 16685
Cylinder 1 Misfire Detected Malfunction P1250 / 17658 "Fuel
Level Too Low" also in DTC memory
No
Yes

- For malfunctions that can be caused by
fuel problems (e.g. fuel system too lean),
the malfunction "Fuel Level Too Low" is
also set if there is less than 12 liters (12.7
qt.) fuel in the tank check tank level and
fill tank if necessary
_______________________
P0302 / 16686
Cylinder 2 Misfire Detected Malfunction cause found: Yes
No

- Erase DTC memory, test drive and check
DTC memory again
_______________________
P0303 / 16687
Cylinder 3 Misfire Detected
_______________________ Are other Diagnostic Trouble
Codes (DTC) present in the DTC
memory (e.g fuel injector, heated
oxygen sensor probes, fuel system
etc.) when combustion misfiring is
recognized
No Yes

- The combustion misfiring that has been
recognized is a resulting malfunction from
the stored Diagnostic Trouble Codes (DTC)
First repair this malfunction according to
Diagnostic Trouble Code (DTC) table
MIL Status:
MIL lights up or blinks
For troubleshooting Display
groups 031, 038, 039
Malfunction cause found: Yes
No
Continued next page

- Erase DTC memory, test drive and check
DTC memory again
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01-65

Output on GST and/or on VAG
1551 scan tool Possible malfunction cause

Malfunction repair
P0300 / 16684
Random Misfire Detected
_______________________
P0304 / 16688
Cylinder 4 Misfire Detected Malfunction P1250 / 17658 "Fuel
Level Too Low" also in DTC
memory
No
Yes

- For malfunctions that can be caused by
fuel problems (e.g. fuel system too lean), the
malfunction "Fuel Level Too Low" is also set
if there is less than 12 liters (12.7 qt.) fuel in
the tank check tank level and fill tank if
necessary
_______________________
P0305 / 16689
Cylinder 5 Misfire Detected Malfunction cause found: Yes
No

- Erase DTC memory, test drive and check
DTC memory again
_______________________
P0306 / 16690
Cylinder 6 Misfire Detected
_______________________ When combustion misfiring is
recognized, are there other
Diagnostic Trouble Codes (DTC)
(e.g. fuel injector, Oxygen Sensor
Proben, Fuel system etc.) in DTC
memory
No Yes

- The combustion misfiring that has been
recognized is a resulting malfunction from
the stored Diagnostic Trouble Codes (DTC)
First repair this malfunction according to
Diagnostic Trouble Code (DTC) table
MIL Status:
MIL lights up or blinks
For troubleshooting Display
groups 031, 038, 039
Malfunction cause found: Yes
No
Continued next page

- Erase DTC memory, test drive and check
DTC memory again
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01-68

Output on GST and/or
on VAG 1551 scan tool Possible malfunction cause

Malfunction repair
P0322 / 16706
Ignition/Distributor Engine
Speed Input Circuit No
Signal Malfunction P1339 / 17747
"Crankshaft Pos./Engine Speed
Sensors Cross connected" also in
DTC memory
No
Yes

- 3-pin harness connector on Crankshaft Position
(CKP) sensor -G4- and engine speed (RPM) sensor
-G28- transposed disconnect both connectors and
connect correctly; installation location page 28
-7

Malfunction cause found: Yes
No

- Erase DTC memory, test drive and check DTC
memory again
MIL Status:
MIL lights up
immediately
Harness connector for engine
speed (RPM) sensor -G28- loose
or corroded due to moisture in the
harness connector

- Check harness connector for tight fit and contact
corrosion, if necessary reconnect and/or clean,
installation page 28
-7

Malfunction cause found: Yes
No

- Erase DTC memory, test drive and check DTC
memory again

Holding socket for engine
speed (RPM) sensor -G28- loose
or -G28- incorrectly adjusted

- Check mounting
- Adjust engine speed bracket page 28
-23

Malfunction cause found: Yes
No
Continued next page

- Erase DTC memory, test drive and check DTC
memory again
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